This is not a new development, I remember hearing about things like that back in the 70's and 80's but the amount of shared training that athletes from all over the world do is pretty cool. There are runners that train in groups, often spending time in multiple countries, swimmers that do the same, athletes from all over attending the same university where they are often teammates on the university teams, the US and Canadian medal winners who are married to each other, etc. You of course have coaches who move (see the Karoli's and their effect on US Women's gymnastics).
Certainly there is a lot of pride for all the athletes to represent their nation, but in a way it is one more thing blurring the lines (and this is a good thing) on nationality at the Olympics. More and more we will see athletes with parents from different countries, training in a third country, under coaches from yet other countries coupled with training partners from even more countries. Making those athletes true products of an international effort.
Some of this is driven by sponsorship money, they set up training groups and camps for their "stable of runners" , some of it by strong university programs that include a great education, some by following great coaches around,